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Spine Advanced Imaging
By Prof. Stelmark
ATLAS (C1)
The first cervical vertebra, the atlas, a name derived from the Greek god who
bore the world upon his shoulders, least resembles a typical vertebra.
Anteriorly, there is no body but simply a thick arch of bone called the anterior
arch. The anterior arch includes a small anterior tubercle.
AXIS (C2)
The most distinctive feature of the second cervical vertebra, the axis, is the
clinically important dens or odontoid process, the conical process that projects
up from the superior surface of the body.Embryologically, the dens is actually the
body of C1, but it fuses to C2 during development. Therefore, it is considered part
of C2 in mature skeletons.
Radiographic demonstration of the relationship of C1 to C2 and the relationship of
C1 to the base of the skull is clinically important because injury this high in the spinal
canal can result in serious paralysis and death.
Normally, articulations between C2 and C1, the zygapophyseal joints, are perfectly
symmetric. Accordingly, the relationship of the dens to C1 also must be perfectly
symmetric. Both injury and improper positioning can render these areas asymmetric.
For example, rotation of the skull can alter the symmetry of these spaces and joints,
thus imitating an injury. Therefore, accurate positioning for this region is essential
A.Centrally located dens
B.Left transverse process of C1
C.Left lateral mass of C1
D.Inferior articular surface of C1
E.Left zygapophyseal joint surface of C2
F.Body of C2
G.Right superior articular
AP “OPEN MOUTH” PROJECTION—C1 AND C2: CERVICAL SPINE
Warning: Do not attempt any head or neck movement if cervical trauma is
possible without first consulting with a physician who has reviewed a horizontal
beam lateral radiograph.
Pathology Demonstrated
Pathology (particularly fractures) involving C1 and C2 and adjacent soft tissue
structures. Demonstrates odontoid and Jefferson fractures.
Patient Position
Position patient in the supine or erect position with arms by sides. Place head
on table surface, providing immobilization if needed.
Part Position
• Align midsagittal plane to CR and midline of table.
• Adjust head so that, with mouth open, a line from lower margin of upper
incisors to the base of the skull (mastoid tips) is perpendicular to table and/or
IR, or angle the CR accordingly.
• Ensure that no rotation of the head or thorax exists.
• Ensure that mouth is wide open during exposure. (Do this as the last step
and work quickly, because it is difficult to maintain this position.)
Central Ray
• CR perpendicular to IR, directed through center of open mouth
• Image receptor centered to CR
• Minimum SID of 40 inches (100 cm)
Collimation
Close four-sided collimation to area of interest, approximately 4 × 4 inches or
10 × 10 cm
Respiration
Suspend respiration.
Note: Make sure that when patient is instructed to open the mouth, only
the lower jaw moves. Instruct the patient to keep the tongue in the lower
jaw to prevent its shadow from superimposing the atlas and axis.
If the upper dens cannot be demonstrated, perform Fuchs
Structures Shown: • Dens (odontoid process) and vertebral body of C2, lateral
masses of C1, and zygapophyseal joints between C1 and C2 should be clearly
demonstrated through the open mouth.
AP OR PA PROJECTION FOR C1-C2 (DENS): CERVICAL SPINE
Fuchs Method (AP)
Warning: Do not attempt this head or neck movement if cervical trauma is
possible without first consulting a physician who has reviewed a lateral
cervical radiograph.
Pathology Demonstrated
Pathology involving the dens and surrounding bony structures of the C1 ring
is demonstrated.
Patient and Part Position
• Supine (AP) or prone (PA) with midsagittal
plane aligned to CR and midline of table and/or
IR
• Elevate chin as needed to bring MML
(mentomeatal line) near perpendicular to
tabletop (adjust CR angle as needed to be
parallel to MML).
• Ensure that no rotation of head exists (angles
of mandible equidistant to tabletop).
• Center IR to projected CR.
• CR is parallel to MML, directed to inferior tip of
mandible.
Collimation
Close four-sided collimation to C1 to C2 region
Respiration
Suspend respiration.
Structures Shown: • Demonstrates the dens (odontoid process) and
other structures of C1 to C2 within the foramen magnum.
AP “WAGGING JAW” PROJECTION: CERVICAL SPINE
Ottonello Method
Warning: Do not attempt this head or neck movement if cervical trauma is possible
without first consulting a physician who has reviewed a lateral cervical radiograph.
Pathology Demonstrated
Pathology involving the dens and surrounding bony structures of the C1 ring, as well
as the entire cervical column, is demonstrated.
Part Position
• Align midsagittal plane to CR and midline
of table and/or IR.
• Adjust head so that a line drawn from
lower margin of upper incisors to the base
of the skull is perpendicular to table.
• Ensure that no rotation of the head or
thorax exists.
• Mandible must be in continuous motion
during exposure.
• Ensure that only the mandible moves.
The head must not move, and the teeth
must not make contact.
Low mA and long (>2 sec) exposure time
Collimation
Four-sided collimation to area of entire
cervical spine
Respiration
Suspend respiration.
Note: Practice with patient before
exposure to ensure that only the
mandible is moving continuously, and
that teeth do not make contact.
ANTERIOR AND POSTERIOR OBLIQUE POSITIONS: CERVICAL SPINE
Warning: Do not attempt any head or neck movement if cervical trauma is possible
without first consulting a physician who has reviewed a horizontal beam lateral
radiograph
Pathology Demonstrated
Pathology involving the cervical spine and adjacent soft tissue structures. Stenosis
involving the intervertebral foramen is demonstrated.
Both right and left oblique projections should be taken for comparison
purposes. Anterior oblique projections are preferred because of reduced thyroid
doses.
Patient Position
The erect position is preferred (sitting or standing), but recumbent is
possible if the patient's condition requires this.
Part Position
• Center spine to CR and midline of table and/or IR.
• Place patient's arms at side; if patient is recumbent, place arms as needed to help
maintain position.
• Rotate body and head 45°.
• Extend chin to prevent mandible from superimposing vertebrae. Elevating chin too
much will superimpose base of skull over C1.
Central Ray
Anterior Obliques
• 15° caudad to C4 (level of upper
margin of thyroid cartilage)
Central Ray
• 15° cephalad to C4 (to lower
thyroid cartilage)
• Image receptor centered to
projected CR SID of 60 to 72 inches
(150 to 180 cm)
Collimation
Collimate lateral borders to soft tissue borders of neck and upper and lower margins
to IR borders.
Respiration
Patient should suspend respiration.
Note: Departmental option: The head may be turned toward IR to a near lateral
position. This results in some rotation of upper vertebrae but may help to
prevent superimposition of vertebrae by mandible.
Structures Shown: • Anterior obliques: intervertebral foramina and pedicles on
the side of the patient closest to the IR. • Posterior obliques: intervertebral
foramina and pedicles on the side of the patientfarthest from the IR.
CERVICOTHORACIC (SWIMMER'S) LATERAL POSITION: CERVICAL SPINE
Pathology Demonstrated
Pathology involving the inferior cervical spine, superior thoracic spine, and adjacent
soft tissue structures. Various fractures (including compression fractures) and
subluxation are demonstrated.
This is a good projection when C7 to T1 is not visualized on the lateral cervical spine,
or when the upper thoracic vertebrae are of special interest on a lateral thoracic
spine.
Patient Position
Erect position is preferred (sitting or
standing), but the radiograph may be done
in the recumbent position if patient's
condition requires this.
Part Position
• Align midcoronal plane to CR and midline
of table and/or IR.
• Place patient's arm and shoulder nearest
IR up, flexing elbow and resting forearm on
head for support.
• Position arm and shoulder away from IR,
down and slightly posterior, to place the
remote humeral head posterior to
vertebrae.
• Maintain thorax and head in as true a
lateral position as possible.
Central Ray
• CR perpendicular to IR
• CR centered to T1, which is approximately 1 inch (2.5 cm) above level of jugular
notch anteriorly and at level of vertebra prominens posteriorly
• IR centered to CR
• SID of 60 to 72 inches (150 to 180 cm)
Collimation
Close four-sided collimation to area of interest
Respiration
Suspend breathing on full expiration.
Note: A slight caudad angulation of 3° to 5° may be necessary to help separate
the two shoulders, especially on a patient with limited flexibility who cannot
sufficiently depress the shoulder away from the IR.
Optional Breathing Technique: If patient can cooperate and remain immobilized, a
low mA and a 3- or 4-second exposure time can be used, with patient breathing short,
even breaths during the exposure to blur out overlying lung structures.
Structures Shown: • Vertebral bodies and intervertebral disk spaces of C4 to T3 are
shown. • The humeral head and arm farthest from the IR are magnified and should
appear distal to T4 or T5 (if visible).
Lumbar Spine
Oblique Lumbar Vertebrae
APPEARANCE OF “SCOTTIE DOG”
Any bone and its parts, when seen in an oblique position, are more difficult to
recognize than the same bone seen in the conventional frontal or lateral view. A
vertebra is no exception; however, imagination can help us in the case of the lumbar
vertebrae. A good 45° oblique projects the various structures in such a way that a
“Scottie dog” seems to appear.
ZYGAPOPHYSEAL JOINTS—OBLIQUE LUMBAR SPINE
Positioning for oblique projections of the lumbar spine requires a good understanding
of the anatomy of the vertebrae and the zygapophyseal joints. It is important to know
how much to rotate the patient and which joint is being demonstrated.
Posterior Oblique
The downside joints are visualized on posterior obliques.
Anterior Oblique
The anterior oblique position may be more comfortable for the patient and may
allow the natural lumbar curvature of the spine to coincide with the divergence of
the x-ray beam. An anterior oblique visualizes the upside joint.
OBLIQUES—POSTERIOR (OR ANTERIOR) OBLIQUE POSITIONS:
LUMBAR SPINE
Pathology Demonstrated:
Defects of the pars interarticularis are demonstrated.
Both right and left obliques obtained.
Shielding
Place contact shield over gonads without obscuring area of interest.
Patient Position
Patient should be semisupine (RPO and [LPO]) or semiprone (RAO and [LAO]).
Part Position
• Rotate body 45° to place spinal column directly over midline of table/grid, aligned to
CR.
• Flex knee for stability and comfort.
• Support lower back and pelvis with radiolucent sponges to maintain position. (This
support is strongly recommended to prevent patients from grasping the edge of
the table, which may result in their fingers being pinched.)
Central Ray
• Direct CR perpendicular to IR.
• Center to L3 at the level of the lower costal margin (4 cm [1½ inches]) above iliac
crest.
• Center 2 inches (5 cm) medial to upside ASIS.
• Center IR to CR.
• Minimum SID is 40 inches (100 cm).
Structures Shown: • Zygapophyseal joints are visible. (RPO and LPO show
downside; RAO and LAO show upside.) • “Scottie dogs” should be visualized, and
zygapophyseal joint should appear open.
PA (AP) PROJECTION: SCOLIOSIS SERIES
Pathology Demonstrated
Degree and severity of scoliosis are shown.
A scoliosis series frequently includes two AP (or PA) images taken for comparison—
one erect and one recumbent.
Shielding
Shield gonadal region without obscuring area of interest. Use breast shields for
young females. Shadow shields placed on collimator may be used as shown in Fig.
10-46 and as evident in Fig. 10-48.
Patient Position
Position patient in the erect and recumbent position, with weight evenly distributed on
both feet for the erect position.
Part Position
• Align midsagittal plane to CR and midline of IR, with arms at side.
• Ensure no rotation of torso or pelvis if possible. (Scoliosis may result in twisting and
rotation of vertebrae, making some rotation unavoidable.)
• Place lower margin of IR a minimum of 1 to 2 inches (3 to 5 cm) below iliac crest
(centering height determined by IR size and/or area of scoliosis).
Central Ray
• CR perpendicular, directed to midpoint of IR
• SID of 40 to 60 inches (100 to 150 cm); longer SID required with larger IR to obtain
required collimation.
Respiration
Suspend breathing on expiration.
Notes: A PA rather than an AP projection is recommended because of the
significantly reduced dose to radiation-sensitive areas, such as female breasts
and the thyroid gland. Studies have shown that this projection results in
approximately 90% reduction in dosage to the breasts.
Scoliosis generally requires repeat examinations over several years for
pediatric patients, with emphasis on the need for careful shielding.
ERECT LATERAL POSITION: SCOLIOSIS SERIES
Structures Best Shown
Spondylolisthesis, degree of kyphosis, or lordosis.
Shielding
Place contact shield or shadow shield over
gonads without obscuring area of interest.
Use breast shields for young females.
Patient Position
Position patient in erect lateral position with
arms elevated, or, if unsteady, grasping a
support in front. The convex side of the
curve is positioned against the IR.
Part Position
• Place pelvis and torso in as true a lateral position as possible.
• Align midcoronal plane of body to CR and midline of IR.
• Lower margin of IR should be a minimum of 1 to 2 inches (3 to 5 cm) below level of
iliac crests (centering determined by IR size and patient size).
Central Ray
• CR perpendicular, directed to midpoint of IR
• SID of 40 to 60 inches (100 to 150 cm); longer SID required with larger IR to obtain
required collimation